Refrigeration cycle device for vehicle

ABSTRACT

A refrigeration cycle device for a vehicle includes a condition detecting unit for detecting a condition that an inner pressure of the refrigerant cycle exceeds a control set pressure, and a pressure reducing unit for reducing a pressure of the refrigerant at a low pressure side of a refrigerant cycle when the condition is detected. For example, when the condition detecting unit detects the condition, the pressure reducing unit starts up a compressor of the refrigerant cycle so as to reduce the pressure at the low pressure side in the refrigerant cycle.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No. 2005-127000 filed on Apr. 25, 2005, and No. 2006-55384 filed on Mar. 1, 2006, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a vehicle refrigeration cycle device using refrigerant containing carbon dioxide (CO₂) as a main component, for example.

BACKGROUND OF THE INVENTION

As one of this type of refrigeration cycle devices is known a refrigeration cycle device equipped with a compressor in which the discharge capacity thereof is variable in accordance with a control amount input from the external and the pressure of refrigerant can be increased up to a supercritical area, a heat radiator for cooling the refrigerant compressed by the compressor, an expansion device for reducing the pressure of the refrigerant cooled by the heat radiator, and an evaporator for evaporating the refrigerant reduced in pressure by the expansion device. According to this refrigeration cycle device, when it is determined that a thermal load at the start time of the device is larger than a predetermined load, the control amount to be input from the external is adjusted so that the discharge amount of the compressor is continuously varied from the minimum state to the maximum state during a predetermined time, whereby abnormal increase of high pressure can be suppressed even at the start time of the refrigerant cycle under a high load, and thus pipes, etc. can be prevented from being damaged (for example, JP-A-2002-71228).

In the above-described refrigeration cycle device, the abnormal increase of the high pressure is suppressed by controlling the output condition of the compressor when the compressor is started, and there is no description on the timing of driving the compressor under the stopped state. Particularly in the refrigeration cycle device for a vehicle, as compared with the increase of the refrigerant pressure due to increase of the ambient temperature such as the outside air temperature or the like, the increase of the refrigerant pressure is more greatly affected by heat occurring from an engine, etc. during travel of the vehicle, so that the increase of the refrigerant pressure when the compressor is under the stopped state causes a more critical problem.

SUMMARY OF THE INVENTION

The present invention has been implemented in view of the foregoing problem, and has an object to provide a refrigeration cycle device for a vehicle that can suppress increase of refrigerant pressure.

Furthermore, the present invention has another object to provide a refrigeration cycle device for a vehicle that can suppress excessive increase of refrigerant pressure by forcedly operating a refrigerant cycle even under the state that a driver does not make any request for actuating the refrigerant cycle.

Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress increase of refrigerant pressure due to afterheat from an engine, an electric motor or the like after the vehicle is stopped.

Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress pressure increase of a refrigerant cycle after stop of an engine serving as a driving force source of the refrigerant cycle or the like by forcedly operating the refrigerant cycle before the engine or the like is stopped.

Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress pressure increase of a refrigerant cycle even after stop of an engine, an electric motor or the like serving as a driving force source of the refrigerant cycle by enabling the refrigerant cycle to be forcedly driven.

According to an aspect of the present invention, a vehicle refrigeration cycle device includes a refrigerant cycle through which refrigerant circulates, a condition detecting unit for detecting a condition that an inner pressure of the refrigerant cycle exceeds a control set pressure, and a pressure reducing means for reducing a pressure of the refrigerant at a low pressure side of the refrigerant cycle when the condition is detected. Accordingly, an increase of the refrigerant pressure due to heat from the engine or the like when the vehicle travels can be suppressed and thus the equipment of the vehicle can be prevented from being damaged.

For example, the control set pressure is set lower than a set value that is set for a lowest withstanding pressure in the refrigerant cycle. In this case, the functions of respective functional parts of the refrigerant cycle can be warranted by setting the control set pressure to be lower than the lowest withstanding pressure set value in the refrigerant cycle.

The refrigerant cycle can include a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle. In this case, the control set pressure is set to be lower than the set pressure of the relief device. The control set pressure can be set to be lower than the set pressure of the relief device for protecting the equipment at the low pressure side of the refrigerant cycle by 0.5 MPa or more. When carbon dioxide is used as a main component of the refrigerant, the control set pressure is set in a range between 7 MPa and 12 MPa. Furthermore, the control set pressure can be set in prospect of an increase of the pressure in the refrigerant cycle. In addition, the control set pressure can be set in prospect of an increase of the pressure in the refrigerant cycle due to residual heat of an engine of the vehicle after an ignition switch of the vehicle is set to OFF.

When the refrigerant cycle includes a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle, the control set pressure is set to be lower than the set pressure of the relief device by 1.0 MPa or more.

Generally, the refrigerant cycle includes a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, and a cooling fan for blowing air to the gas cooler. In this case, the pressure reducing means starts up at least one of the cooling fan and the compressor by a control unit when the condition detecting unit detects the condition, and reduces the refrigerant pressure at the low pressure side in the refrigerant cycle. Therefore, the refrigerant pressure due to environment condition can be effectively reduced.

As the compressor, a displacement variable compressor can be used. In this case, the pressure reducing means starts up the displacement variable compressor while a discharge capacity of the displacement variable compressor is controlled by the control unit when the condition detecting unit detects the condition.

The pressure reducing means can start up the compressor when the condition detecting unit detects the condition while an engine of the vehicle is operated under a state where an ignition switch of the vehicle is set to ON.

Alternatively, the compressor can be constructed with an electrical compressor driven electrically. In this case, the condition detecting unit detects the condition under a state where an ignition switch of the vehicle is set to OFF.

The refrigerant cycle can be provided with a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, an evaporator for evaporating refrigerant after being decompressed, a first fan for blowing air to the gas cooler, and a second fan for blowing air to the evaporator. In this case, when the condition detecting unit detects the condition, at least one of the first fan and the compressor is driven and the second fan is stopped by the control unit.

The condition detecting unit can include a pressure detecting unit for detecting whether the refrigerant pressure in the refrigerant cycle reaches a predetermined value. For example, the pressure detecting unit is a discharge pressure sensor for detecting the refrigerant pressure at a discharge side of the compressor in the refrigerant cycle.

Alternatively, the condition detecting unit can include a first temperature detecting unit for detecting whether a refrigerant temperature in the refrigerant cycle reaches a predetermined value. In this case, the first temperature detecting unit includes a discharge temperature sensor for detecting a refrigerant temperature at a discharge side of the compressor of the refrigerant cycle. Furthermore, the first temperature detecting unit can include at least one of a post-evaporation temperature sensor for detecting a temperature of air passed through the evaporator of the refrigerant cycle, a fin temperature sensor for detecting a temperature of a fin of the evaporator, and an air blow-out temperature sensor for detecting a temperature of air to be blown into a passenger compartment of the vehicle.

In addition, the condition detecting unit can include a second temperature detecting unit for detecting whether any one of a temperature in an engine compartment of the vehicle and a temperature in a passenger compartment of the vehicle reaches a predetermined value. For example, the second temperature detecting unit determines the temperature of the passenger compartment based on at least one of detection values of an inside air temperature sensor for directly detecting the temperature of air in the passenger compartment, an outside air temperature sensor for indirectly detecting the temperature in the passenger compartment, and a solar radiation temperature sensor for detecting a solar radiation amount entering into the passenger compartment. Alternatively, the second temperature detecting unit determines on the basis of the detection value of any one of an engine water temperature and an engine intake air temperature whether the temperature in the engine compartment reaches the predetermined value.

In the present invention, the condition detecting unit can be provided with a stop time detecting unit for detecting whether a stop time of the compressor of the refrigerant cycle reaches a predetermined time.

According to another aspect of the preset invention, the control unit starts up at least one of a cooling fan for blowing air to a gas cooler, and a compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when a predetermined time elapses. Therefore, the above-described object can be achieved.

Alternatively, the control unit starts up at least one of the cooling fan for blowing air to the gas cooler and the compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that the refrigerant pressure in the refrigerant cycle is equal to a predetermined value or less.

Alternatively, the control unit starts up at least one of the cooling fan for blowing air to the gas cooler and the compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that the refrigerant temperature in the refrigerant cycle is equal to a predetermined value or less, or any one of a post-evaporation temperature, a fin temperature and an air blow-out temperature is equal to a predetermined value or less.

Alternatively, the control unit starts up at least one of the cooling fan for blowing air to the gas cooler and the compressor of the refrigerant cycle when the condition is detected, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that a temperature in an engine compartment of the vehicle or a temperature in a passenger compartment of the vehicle is equal to a predetermined value or less.

Even in those cases, when a predetermined time elapses after at least one of the compressor of the refrigerant cycle and the cooling fan is stopped, the condition detecting unit starts the detection. Alternatively, when control unit determines the refrigerant pressure in the refrigerant cycle is equal to a predetermined value or less after at least one of the compressor and the cooing fan is stopped, the condition detecting unit starts the detection. Alternatively, when the control unit determines that any one of the refrigerant temperature in the refrigerant cycle reaches a predetermined value or the post-evaporation temperature, the fin temperature and the air blow-out temperature reaches a predetermined value after at least one of the compressor and the cooling fan is stopped, the condition detecting unit starts the detection.

Alternatively, when the control unit determines that the temperature in the engine compartment of the vehicle or a temperature in the passenger compartment of the vehicle is equal to a predetermined value or less after at least one of the compressor and the cooling fan is stopped, the condition detecting unit starts the detection.

In the refrigerant cycle devise, the refrigerant cycle can use refrigerant containing carbon dioxide as a main component.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments made with reference to the accompanying drawings, in which:

FIG. 1 is a diagram showing the construction of a refrigeration cycle device for a vehicle according to a first embodiment of the present invention;

FIG. 2 is a time chart showing the variation of refrigerant pressure in a refrigerant cycle when a compressor is controlled in the vehicle refrigeration cycle device according to the first embodiment;

FIG. 3 is a control flowchart of the processing of controlling the compressor on the basis of a refrigerant pressure detection value to reduce a refrigerant pressure in the vehicle refrigeration cycle device according to the first embodiment;

FIG. 4 is a time chart showing the variation of the refrigerant pressure in the refrigerant cycle when a cooling fan is controlled in the vehicle refrigeration cycle device according to the first embodiment;

FIG. 5 is a control flowchart of the processing of controlling the cooling fan on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure in the vehicle refrigeration cycle device according to the first embodiment;

FIG. 6 is a time chart showing the variation of the refrigerant pressure in the refrigerant cycle when the cooling fan and the compressor are controlled in the vehicle refrigeration cycle device according to the first embodiment;

FIG. 7 is a control flowchart showing the processing of controlling the cooling fan and the compressor on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure in the vehicle refrigerant cycle according to the first embodiment;

FIG. 8 is a diagram showing the construction of a vehicle refrigeration cycle device for a vehicle according to a second embodiment;

FIG. 9 is a diagram showing the construction of another vehicle refrigeration cycle device according to the second embodiment;

FIG. 10 is a diagram showing the construction of the vehicle refrigeration cycle device controlled on the basis of various kinds of data associated with an engine in the vehicle refrigeration cycle device of the second embodiment;

FIG. 11 is a time chart showing the relationship between the variation of the refrigerant temperature or various kinds of monitor temperature and the variation of the refrigerant pressure in the vehicle refrigeration cycle device according to the second embodiment;

FIG. 12 is a control flowchart showing the processing of controlling the compressor on the basis of various kinds of temperature data to reduce the refrigerant pressure in the vehicle refrigeration cycle device according to the second embodiment;

FIG. 13 is a control flowchart showing the processing when the compressor, etc. are stopped on the basis of the refrigerant pressure detection value in the vehicle refrigeration cycle devices according to the first, second and third embodiments of the present invention;

FIG. 14 is a control flowchart showing the processing of stopping the compressor, etc. on the basis of the various kinds of temperature data in the vehicle refrigeration cycle devices according to the first, second and third embodiments;

FIG. 15 is a control flowchart showing the processing of determining a detection start timing of a condition detecting unit on the basis of the time lapse in the vehicle refrigeration cycle devices according to the first, second and third embodiments;

FIG. 16 is a control flowchart showing the processing of determining the detection start timing of the condition detecting unit on the basis of the detection value of the refrigerant pressure in the vehicle refrigeration cycle devices according to the first, second and third embodiments;

FIG. 17 is a control flowchart showing the processing of determining the detection start timing of the condition detecting unit on the basis of various kinds of temperature data in the vehicle refrigeration cycle devices according to the first, second and third embodiments;

FIG. 18 is a control flowchart showing the processing of controlling an electrically-driven compressor on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure when an ignition switch is under off state in the vehicle refrigeration cycle device according to the third embodiment;

FIG. 19 is a control flowchart showing the processing of controlling an electrically-driven cooling fan on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure under the state that the ignition switch is turned off;

FIG. 20 is a control flowchart showing the processing of controlling the electrically-driven cooling fan on the basis of the various kinds of temperature data when the ignition switch is under off state; and

FIG. 21 is a control flowchart showing the processing of controlling the electrically-driven cooling fan on the basis of the time lapse to reduce the refrigerant pressure when the ignition switch is under off state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments according to the present invention will be described hereunder with reference to the accompanying drawings.

First Embodiment

A refrigeration cycle device for a vehicle according to a first embodiment carries out inherent control to reduce refrigerant pressure in a refrigerant cycle using refrigerant containing carbon dioxide (CO₂) as a main component so that parts in the refrigerant cycle can be prevented from being damaged due to increase of the refrigerant pressure. Particularly, the refrigeration cycle device for a vehicle is peculiar and different from a stationary refrigeration cycle device in that the increase of the refrigerant pressure is greatly affected by heat occurring when a vehicle engine is driven unlike.

In order to solve the problem under such a peculiar condition, the vehicle refrigeration cycle device of this embodiment is controlled in consideration of the effect of heat occurring when the vehicle travels. Particularly, one factor causing the increase of the refrigerant pressure in the refrigerant cycle which is applied to the vehicle environment is as follows. That is, when the vehicle is stopped or the engine is stopped after the engine is driven for a long time under a high load state such as a high-speed driving state or the like, and thus introduction of cooling air into an engine compartment is stopped or reduced, the heat of the engine body or the exhaust pipe is diffused into the engine compartment (engine-mounted space) and thus the parts of the refrigeration cycle device are warmed, so that the refrigerant temperature is increased.

In a supercritical refrigerant cycle using carbon dioxide (CO₂) as a main component as in the case of this embodiment, the refrigerant in the refrigerant cycle falls into a supercritical state due to heat radiation from the engine compartment side, retention of heat, increase of the outside air temperature, etc. because of traveling of the vehicle at the time when the cycle is stopped, and the pressure in the cycle is increased, so that the pressure may exceed the withstanding pressure of parts at the low-pressure side. Therefore, a relief device is provided to the low-pressure side, that is, for example, the suction side of the compressor.

Here, the first embodiment will be described hereunder with reference to FIGS. 1 to 7.

FIG. 1 is a diagram showing the construction of the vehicle refrigeration cycle device according to this embodiment. As shown in FIG. 1, the refrigerant cycle 1 is equipped with a compressor 8, a discharge pressure sensor 9 as one example of a pressure detecting unit for detecting the refrigerant pressure at the high pressure side, a gas cooler 3 corresponding to a high-pressure side heat exchanger, an expansion valve 4 serving as a pressure reducing unit, an evaporator 5 corresponding to a low-pressure side heat exchanger, a low-pressure side pressure sensor 9a for detecting the refrigerant pressure at the low-pressure side of the refrigerant cycle, an accumulator 6 for separating the refrigerant into gas-phase refrigerant and liquid-phase refrigerant and feeding the gas-phase refrigerant to the suction portion of the compressor 8, and a relief device 7 disposed at the low-pressure side corresponding to the suction portion side of the compressor 8, which are successively and annularly connected to one another through pipes.

At least one of the compressor 8, the gas cooler 3, the evaporator 5 and the accumulator 6 constituting the vehicle refrigerant cycle is disposed in an engine compartment (engine mount space). Furthermore, the gas cooler 3 is provided with a cooling fan 2 to be opposite with each other.

The compressor 8 is driven by a belt interlocked with the engine to compress the gas-phase refrigerant sucked from the accumulator 6 under the critical pressure or more and discharge the compressed refrigerant. The compressor 8 is controlled by a controller 10 (CEU) described later, and the rotation of the compressor 8 is driven by the engine or electrically driven by an in-vehicle mount battery.

The compressor 8 may be a displacement variable compressor. In this case, the controller 10 controls current supplied to the displacement variable compressor to control the discharge capacity of the displacement variable compressor, thereby controlling the refrigerant pressure.

The discharge pressure sensor 9 is disposed between the compressor 8 and the gas cooler 3, and detects the refrigerant pressure in the refrigerant cycle 1. The detection value of the discharge pressure sensor 9 when the compressor 8 is stopped is transmitted to the controller 10. When the detection value is about to exceed a predetermined control set pressure of the refrigerant cycle 1, in order to reduce the refrigerant pressure, the controller 10 starts actuation of the compressor 8 to make the refrigerant flow in the cycle to thereby reduce the refrigerant pressure as an example of the pressure reducing unit.

The control set pressure may be set to a value lower than the lowest withstanding pressure set value in the refrigerant cycle 1 or a value lower than the set pressure of the relief device 7 for protecting the equipment. Furthermore, in place of the compressor 8, the cooling fan 2 may be started to cool the gas cooler 3, thereby cooling the refrigerant in the gas cooler 3, so that the inner pressure of the refrigerant cycle can be avoided from increasing. The control set pressure is set to a proper value in prospect of increase of the pressure in the refrigerant cycle in consideration of the variation of the pressure increase in the refrigerant cycle in accordance with the specification of the refrigerant cycle mounted in the vehicle.

When the vehicle is stopped and further the engine is also stopped after the vehicle travels under a high engine load (high-speed traveling, climbing traveling or the like) at a high outside air temperature, the temperature in the engine compartment is increased, and the pressure increase of 0.5 MPa or more may appear in the refrigerant cycle 1. Accordingly, the control set pressure is preferably set to a value lower than the set pressure of the relief device 7 for protecting the equipment at the low pressure side of the refrigerant cycle 1 by 0.5 MPa or more.

The control set pressure is preferably set in consideration of the tolerance of the relief device 7. For example, when the set pressure value of the relief device is equal to 11 MPa and the tolerance is equal to ±0.5 MPa, the control set value is set to 10.5 MPa or less.

Furthermore, it has been verified through in-vehicle tests that the maximum pressure increase in the refrigerant cycle is equal to about 1.0 MPa, and thus the control set pressure is preferably set to a value lower than the set pressure of the relief device 7 by 1.0 MP or more. For example, when the set pressure value of the relief device 7 is equal to 11 MPa, the control set pressure is set to 10.0 MPa or less.

Furthermore, the control set pressure is preferably set within the range from 7 to 12 MPa which is lower than the set pressure of the relief device 7 by 0.5 MPa or more. 7 MPa is the refrigerant pressure at the ambient temperature of the refrigerant cycle of about 30° C. when the refrigerant enclosed density of the refrigerant cycle is considered from the refrigerant enclosed amount. In the case that the control set pressure is set to 7 MPa or less, when the engine is started at the outside temperature of 30° C. or less, the compressor absolutely starts its operation. However, there may be considered such a situation that some passenger does not start the air conditioner if the outside air temperature is equal to a level about 30° C. Therefore, if the control set pressure is set to 7 MPa or less, the compressor starts to operated against the passenger's intention, which causes deterioration of the fuel consumption of the vehicle. Accordingly, in order to avoid such a situation, the control set pressure is preferably set to 7 MPa or more.

The gas cooler 3 heat-exchanges the high-pressure/high-temperature refrigerant discharged from the compressor 8 with air blown out from the cooling fan 2, so that the refrigerant is condensed and liquefied.

The cooling fan 2 cools the gas cooler 3, and it is constructed by an electrically-driven cooling fan, an engine direct-coupled type coupling fan or a fan driven by a hydraulic driving motor. The cooling fan 2 may be designed to be also used a radiator cooling fan or to be used exclusively for the gas cooler 3. Furthermore, the cooling fan 2 may be secured integrally with the gas cooler 3, or fixed to a part at the vehicle side.

The expansion valve 4 is a pressure reducing unit for isenthalpically reducing the pressure of the refrigerant flowing out from the gas cooler 3 in accordance with the valve opening degree. Specifically, it more greatly reduces the pressure of the refrigerant by reducing the valve opening degree. The expansion valve 4 mechanically controls the high-pressure side refrigerant pressure on the basis of the refrigerant temperature at the exit of the gas cooler.

The evaporator 5 is cooled by the gas cooler 3, and it serves as a heat-exchanger in which the liquid refrigerant kept under the low-temperature and low-pressure state by the expansion valve 4 is evaporated by absorbing heat from the outside air. The air passing over the outside of the evaporator 5 is robbed of its heat and thus cooled, and also the air is humidified. The cooled and dehumidified air is fed as cooling air into the room of the vehicle by an air blowing fan (not shown).

The accumulator 6 subjects the refrigerant flowing out from the evaporator 5 to gas-liquid separation so that only the gas-phase refrigerant is sucked into the compressor 8, and the accumulator 6 also serves as a receiver for accumulating the extra refrigerant in the refrigerant cycle.

The relief device 7 serves to carry out relief so that the inner pressure of the cycle does not exceed the design pressure of the low-pressure side parts not only at the high-pressure side, but also at the low-pressure side. For example, a valve type is used as the relief device 7, in the refrigerator cycle using a carbon dioxide (CO₂) refrigerant.

The operation of the ignition switch 11, the detection value of the discharge pressure sensor 9, the detection value of the low-pressure side pressure sensor 9 a, the operation state of the compressor 8 and the operation condition of the cooling fan 2 are input to the controller 10 serving as the control unit of this embodiment, and the operation of an air conditioner switch (not shown) is also input to the controller 10. The controller 10 is equipped with a timer 12, and it can count the time lapse, etc. of the driving or stopping of each part constituting the refrigerant cycle 1. The controller 10 controls the compressor 8, the cooling fan 2, etc. on the basis of various kinds of input data and preset programs.

In FIG. 1 of this embodiment, the refrigeration cycle device is equipped with both of the discharge pressure sensor 9 corresponding to an example of the pressure detecting unit for detecting the refrigerant pressure at the high pressure side and the low-pressure side pressure sensor 9 a for detecting the refrigerant pressure at the low pressure side, however, the refrigeration cycle device may be equipped with any one of the sensors as the pressure detecting means insofar as it has the action and effect of the present invention.

Next, the operation of the vehicle refrigeration cycle device according to this embodiment will be described. The main operation of the vehicle refrigeration cycle device is carried out under the state that the ignition (IG) switch is set to ON or the engine is driven and also the compressor for the refrigerant cycle is stopped.

Pressure reducing processing of reducing the refrigerant pressure is carried out when a condition detecting unit detects some conditions and a pressure reducing unit is actuated, stop condition detecting processing is carried out, and then pressure reducing cancel processing of stopping the pressure reducing operation of the pressure reducing unit is carried out. Thereafter, reset processing is carried out until the condition detecting unit starts the detection, and then the processing returns to the pressure reducing processing.

First, a case, where the compressor 8 is started as the pressure reducing unit when the condition detecting unit detects such a condition that the pressure exceeds the control set pressure of the refrigerant cycle, will be described with reference to FIGS. 2 and 3.

FIG. 2 is a time chart showing the variation of the refrigerant pressure in the refrigerant cycle 1 when the compressor 8 is controlled, and FIG. 3 is a flowchart showing the control processing when the compressor 8 is controlled on the basis of a refrigerant pressure detection value to reduce the refrigerant pressure (routine A). In FIG. 2 and other figures, P(RELIEF) indicates set pressure of the relief device 7.

As shown in FIG. 3, first, when the ignition (IG) switch is set to ON or the engine is driven (step S100), it is determined whether the compressor 8 is stopped or not (step S111). When the compressor 8 is driven, some difference occurs between the refrigerant pressure at the high pressure side of the refrigerant cycle 1 and the refrigerant pressure at the low pressure side of the refrigerant cycle 1 (see FIG. 2).

If it is determined in step S111 that the compressor 8 is not stopped, the determination of the step S111 is repeated again. Here, if it is determined that the compressor 8 is stopped, the detection of the condition detecting unit is started after a predetermined time t1′, thereby carrying out the reset processing. At this time, the difference occurring between the refrigerant pressure at the high pressure side in the refrigerant cycle 1 and the refrigerant pressure at the low pressure side in the refrigerant cycle 1 is reduced with the time lapse from the stop of the compressor 8, and finally both the refrigerant pressure values become equal to each other. Then, the refrigerant pressure thus equalized is increased by heat radiation from an engine compartment, retention of heat, etc. due to driving of the engine at the vehicle travel time or the like (see FIG. 2).

It is determined in step S112 whether the refrigerant pressure P based on the detection of the discharge pressure sensor 9 is above a predetermined value P′. If it is determined that the refrigerant pressure reaches the predetermined value P′, the processing of starting up the compressor 8 (step S113) is performed. If it is determined that the refrigerant pressure P does not reach the predetermined value P′, the determination of the step S112 is repeated again. At this time, the refrigerant pressure in the refrigerant cycle 1 is divided into that at the high pressure side and that at the low pressure side in connection with the driving of the compressor 8, and a pressure difference occurs between both the refrigerant pressure values (see FIG. 2).

Furthermore, after the compressor 8 is started up, the counting of a timer t2 is started by the timer 12 (step S114). In step S115, the counting of the timer t2 is continued until it reaches t2′ and if it is determined that the counting of the timer t2 reaches t2′, the compressor 8 during operation is stopped (step S116). With respect to the refrigerant pressure in the refrigerant cycle 1, a pressure difference occurring between that at the high pressure side and that at the low pressure side is reduced because the refrigerant pressure at the high pressure side is reduced and the refrigerant pressure at the low pressure side is increased in connection with the stop of the compressor 8. Therefore, both the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side become equal to each other, and thus the refrigerant pressure is made uniform. Accordingly, the refrigerant pressure is controlled to a value lower than the control set pressure as a whole (see FIG. 2).

Thereafter, the processing goes to linked processing indicated by a link mark K in FIG. 3 to advance to a determination of step S155 of FIG. 16 or a determination of step S160 of FIG. 17 shown in a second embodiment, whereby the processing goes to a step of starting the detection of the condition detecting unit.

As described above, if the refrigerant pressure in the refrigerant cycle 1 is kept to a value lower than the control set pressure, the equipment in the refrigerant cycle 1 can be prevented from being damaged. However, when the refrigerant pressure in the refrigerant cycle 1 is likely to fall into the condition that it exceeds the control set pressure because of the effects of the outside air temperature, the head radiation from the engine compartment, heat retention, etc. due to the driving of the engine at the vehicle travel time or the like, the processing of the step S113 is executed again and the compressor 8 is started up in order to prevent the equipment in the refrigerant cycle 1 from being damaged.

The control set pressure is a predetermined value pre-programmed in the controller 10, and it may be set to a value lower than the lowest withstanding pressure in the refrigerant cycle 1 or a value lower than the set pressure of the relief device 7. The relief device 7 is disposed at the lower pressure side of the refrigerant cycle 1, and in this case the set pressure of the relief device 7 corresponds to the function-warrantable pressure for the equipment provided to the low pressure side of the refrigerant cycle 1 which covers the area extending from the downstream side of the expansion valve 4 to the suction portion of the compressor 8.

Furthermore, the set pressure has a constant range because the relief is required to work surely, and it represents a range of pressure in which the relief would blow out. This value is set in consideration of the tolerance of the relief, the effect of the aged variation of the device, etc. For example, in the case that the set pressure is equal to 11 MPa, when the product tolerance is equal to ±0.5 MPa and the deviation of the set value due to the aged variation is equal to ±0.5 MPa, the pressure reducing unit works under at least the pressure lower than 10 MPa.

Furthermore, the compressor 8 may be constructed by a displacement variable compressor, and when the condition is detected, the controller 10 may control the capacity of the displacement variable compressor to start up the compressor. This is carried out to prevent rapid increase of the refrigerant pressure at the high pressure side. Specifically, at the initial stage of the driving, the displacement variable compressor is driven by applying some current value to the compressor, and thereafter the capacity of the compressor is varied while the discharge pressure is subjected to feedback control. Furthermore, when an electrically-driven compressor is used, the same effect can be achieved by controlling the rotational number of the motor.

Next, a case where the cooling fan 2 is started up in place of the start-up of the compressor 8 when the condition is detected will be described. FIG. 4 is a time chart showing the variation of the refrigerant pressure in the refrigerant cycle when the cooling fan 2 is controlled. FIG. 5 is a flowchart showing the control processing of controlling the cooling fan 2 on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure (routine B).

As shown in FIG. 5, first, when the ignition (IG) switch is set to ON or the engine is driven (step S100), it is determined whether the compressor 8 is stopped or not (step S111). When the compressor is driven, the refrigerant pressure in the refrigerant cycle 1 has some difference between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side (see FIG. 4).

If it is determined in step S111 that the compressor 8 is not stopped, the determination of the step S111 is repeated again. If it is determined in step S111 that the compressor 8 is stopped, after a predetermined time t1′ described later, the detection of the condition detecting unit is started, thereby carrying out the reset processing. At this time, the difference occurring between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side in the refrigerant cycle 1 is reduced with time lapse from the stop of the compressor 8, and both the refrigerant pressure values are finally equal to each other (i.e., the refrigerant pressure is made uniform).

It is determined in step S112 whether the refrigerant pressure P based on the detection of the discharge pressure sensor 9 is above a predetermined value P′. Then, the refrigerant pressure P thus equalized is increased by heat radiation from an engine compartment, retention of heat, etc. due to start-up of the engine at the vehicle travel time or the like (see FIG. 4).

If it is determined that the refrigerant pressure P reaches the predetermined value P′, the processing of starting up the cooling fan 2 is carried out (step S117). If it is determined that the refrigerant pressure P does not reach the predetermined value P′, the determination of the step S112 is repeated again. The refrigerant pressure P in the refrigerant cycle 1 is controlled to be lower than the predetermined value P′ because the refrigerant is cooled by the start-up of the cooling fan 2 (see FIG. 4). Furthermore, after the cooling fan 2 is started up, the count of the timer t2 is started by the timer 12 (step S114).

In step S115, the counting of the timer t2 is continued until the count value reaches t2′, and if it is determined that the count of the timer t2 reaches t2′, the cooling fan 2 under operation is stopped (step S118). The refrigerant pressure in the refrigerant cycle 1 which has been lower than the predetermined value P′ begins to gradually increase again due to the effect of the outside air temperature and the heat radiation from the engine compartment, the heat retention, etc. due to the driving of the engine at the vehicle travel time or the like in connection with the stop of the compressor 8 (see FIG. 4).

Thereafter, the processing goes to linked processing indicated by the linking mark K in FIG. 3 to advance to a determination of step S155 of FIG. 16 or a determination of step S160 of FIG. 17 shown in the second embodiment, whereby the processing goes to a step of starting the detection of the condition detecting unit.

As described above, if the refrigerant pressure in the refrigerant cycle 1 is kept to a value lower than the control set pressure, the equipment in the refrigerant cycle 1 can be prevented from being damaged. However, when the refrigerant pressure in the refrigerant cycle 1 is likely to fall into the condition that it exceeds the control set pressure because of the effects of the outside air temperature, the head radiation from the engine compartment, heat retention, etc. due to the driving of the engine at the vehicle travel time or the like, the processing of the step S117 is executed again and the cooling fan 2 is started up in order to prevent the equipment in the refrigerant cycle 1 from being damaged.

The cooling fan 2 may be constructed by a variable type fan, and when the condition is detected, the controller 10 may control the input to the variable type cooling fan to start up the cooling fan. This is carried out to promote reduction of the refrigerant pressure more efficiently. Specifically, at the initial stage of the driving of the cooling fan, some input value is input to the cooling fan 2 to start up the cooling fan, and then the input value is varied while the discharge pressure is subjected to feedback control, thereby controlling the rotational number of the cooling fan 2.

At the condition detection time, the controller 10 preferably stops the air blowing fan for blowing air to the evaporator 5 in addition to the start-up of at least one of the cooling fan 2 and the compressor 8 for the refrigerant cycle.

Next, a case where the cooling fan 2 and the compressor 8 are stepwise driven at the condition detection time will be described.

FIG. 6 is a time chart showing the variation of the refrigerant pressure in the refrigerant cycle when the cooling fan 2 and the compressor 8 are controlled. FIG. 7 is a flowchart showing the control processing of controlling the cooling fan 2 and the compressor 8 on the basis of the refrigerant pressure detection value to reduce the refrigerant pressure (routine C).

As shown in FIG. 7, first, when the ignition (IG) switch is set to ON or the engine is driven (step S100), it is determined whether the compressor 8 is stopped (step S111). When the compressor 8 is driven, the refrigerant pressure in the refrigerant cycle 1 has some difference between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side (see FIG. 6).

If it is determined in step S111 that the compressor 8 is not stopped, the determination of the step S111 is repeated again. If it is determined that the compressor 8 is stopped, after a predetermined time t1′ described later elapses, the detection of the condition detecting unit is started, thereby carrying out the reset processing. At this time, the difference occurring between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side is gradually reduced with time lapse from the stop of the compressor 8, and both the refrigerant pressure values are finally equal to each other.

It is determined in step S120 whether the refrigerant pressure P based on the detection of the discharge pressure sensor 9 is above a predetermined value P1. Then, the refrigerant pressure P thus equalized is increased by heat radiation from an engine compartment, retention of heat, etc. due to driving of the engine at the vehicle travel time or the like (see FIG. 6).

If it is determined that the refrigerant pressure P reaches the predetermined value P1, the processing of starting up the cooling fan 2 is carried out (step S121). If it is determined that the refrigerant pressure P does not reach the predetermined value P1, the determination of the step S120 is repeated again. At this time, when a sufficient cooling effect cannot be achieved even by starting up the cooling fan 2 and the refrigerant pressure P in the refrigerant cycle 1 further increases over the predetermined value P1, the condition detecting unit carries out the pressure determination on the basis of the detection value from the discharge pressure sensor 9 (see FIG. 6).

Subsequently, it is determined in step S122 whether the refrigerant pressure P is equal to or more than a predetermined value P2. If it is determined that the refrigerant pressure reaches the predetermined value P2, the processing of starting up the compressor 8 is carried out (step S123). The predetermined value P2 is higher than the predetermined value P1. At this time, the cooling fan 2 may be stopped simultaneously with the start-up of the compressor 8 or continually driven. At this time, the refrigerant pressure in the refrigerant cycle 1 is divided into the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side in connection with the start-up of the compressor 8, and a pressure difference occurs between both the refrigerant pressure values (see FIG. 6).

Furthermore, after the compressor 8 is started up, the counting of the timer t2 is started by the timer 12 (step S124), and the counting is continued until the counting of the timer t2 reaches t2′ in step S125. If it is determined that the counting of the timer t2 reaches t2′, the compressor 8 during operation is stopped (step S126). At this time, the cooling fan 2 may be stopped or continually driven in connection with the start-up of the compressor 8.

With respect to the refrigerant pressure in the refrigerant cycle 1 in which a pressure difference occurs between that at the high pressure side and that at the low pressure side, in connection with the stop of the compressor 8, the refrigerant pressure at the high pressure side is reduced, and the pressure at the low pressure side is increased, so that the pressure difference is reduced and both the refrigerant pressure values become equal to each other. Thereafter, the processing goes to the linked processing indicated by the linking mark K and advances to the determination of step S155 of FIG. 16 or the determination of step S160 of FIG. 17 in the second embodiment, thereby going to the step of starting the detection of the condition detecting unit.

As described above, if the refrigerant pressure in the refrigerant cycle 1 is kept to a value lower than the control set pressure, the damage of the equipment in the refrigerant cycle 1 can be prevented. However, when the refrigerant pressure in the refrigerant cycle 1 is likely to fall into the condition that it exceeds the control set pressure because of the effects of the outside air temperature, the head radiation from the engine compartment, heat retention, etc. due to the driving of the engine at the vehicle travel time or the like, the processing of the step S121 is executed again and the cooling fan 2 is started up in order to prevent the equipment in the refrigerant cycle 1 from being damaged.

As shown in FIGS. 3, 5 and 7, in place of use of the pressure reducing unit for reducing the refrigerant pressure by starting up the compressor 8 or the cooling fan 2 when the detection pressure increases to the predetermined value or more, the refrigerant pressure may be reduced by a pressure reducing unit that regards the refrigerant pressure as increasing and falling into a high pressure state when a predetermined time elapses and reduces the refrigerant pressure.

The time t1′ from the stop of the compressor 8 to the start-up of the compressor 8 may be controlled to vary in accordance with the outside air temperature. For example when the outside air temperature is equal to 30° C. or more, t1′ is set to 5 minutes. When the outside air temperature is less than 30° C., the compressor 8 is controlled not to be started up.

As described above, the vehicle refrigeration cycle device according to this embodiment is equipped with the discharge pressure sensor 9 and the controller 10. The discharge pressure sensor 9 serving as the condition detecting unit detects the condition that the refrigerant pressure is likely to exceed the control set pressure of the refrigerant cycle 1 when the engine of the vehicle is driven or the ignition switch of the vehicle is set to ON and the driving of the compressor 8 for the refrigerant cycle is stopped. Furthermore, the controller 10 is set for driving at least one of the compressor 8 and the cooling fan 2 to reduce the refrigerant pressure at the low pressure side of the refrigerant cycle 1. Furthermore, the control set pressure is set in prospect of the increase of the pressure in the refrigerant cycle 1 after the ignition switch is set to OFF.

According to the above construction, the increase of the refrigerant pressure due to the heat from the engine, etc. at the vehicle travel time can be suppressed, and the damage of the equipment constituting the refrigerant cycle 1 can be prevented before happens.

Furthermore, according to the vehicle refrigeration cycle device thus constructed, there is no restriction to the refrigerant sealing density in the refrigerant cycle, and the cycle can be protected even when the sealing density is large. Since the sealing density is allowed to be large, the cycle capacity may be small with respect to the sealed refrigerant amount, and thus the body size of the functional part can be reduced.

For example, the capacity size of the accumulator can be designed to be small, so that it contributes to provision of an accumulator having a low cost and an excellent mount performance. Furthermore, assuming that when the required refrigerant amount of the cycle is desired to be set to 500 g and the sealing density is desired to be set to 260 kg/m³, the accumulator capacity is equal to 750 cc, if even 300 kg/m³ is allowed for the sealing density of the cycle, the capacity of the accumulator is equal to 500 cc, and thus the body size of the accumulator can be reduced.

Furthermore, when the control set pressure is set to be lower than the lowest withstanding set pressure in the refrigerant cycle 1, a vehicle refrigeration cycle device with which the protection for the function of the respective function parts can be warranted is achieved.

Furthermore, when the control set pressure is set to be lower than the set pressure of the relief device 7 for protecting the equipment at the low pressure side constituting the refrigerant cycle 1, the refrigerant cycle can be protected without making the relief function under the increase of the refrigerant pressure at high temperature.

Still furthermore, the condition detection for detecting the condition that the pressure in the refrigerant cycle is likely to exceed the control set pressure is carried out under the state that the ignition switch of the vehicle is set to ON and the engine is driven. Furthermore, the pressure reducing unit executes the processing of reducing the refrigerant pressure when the condition is detected, that is, the engine is driven.

When the above control is carried out, by starting up the compressor during the driving of the engine, the inner pressure can be prevented from increasing when the engine is off. That is, after the engine is stopped, the temperature is retained in the inner pressure of the engine compartment, and thus the ambient temperature of the refrigerant cycle is increased, so that the refrigerant pressure is also increased.

For example, when the refrigerant pressure is equal to 10.5 MPa at the stop time of the vehicle, it is increased by the effect of the temperature of the engine compartment. When the control set pressure is equal to 11 MPa, the relief starts up. By starting up the compressor during the driving of the engine, the pressure at the stop time of the vehicle is suppressed to about 9 MPa. Therefore, even when the inner temperature of the engine compartment is high, the increasing degree of the pressure of the refrigerant cycle can be dampened. Since the inner temperature of the engine compartment is gradually reduced to the ambient temperature, the peak pressure of the refrigerant pressure of the refrigerant cycle is lower as compared with the case where the compressor is not started up, and thus it is unnecessary to start up the relief.

Furthermore, when the controller 10 starts up at least one of the compressor 8 for the refrigerant cycle and the cooling fan 2 at the condition detection time, the refrigerant pressure can be directly reduced by driving the compressor 8. Furthermore, by driving the cooling fan 2, the refrigerant temperature in the gas cooler serving as the high-pressure side heat exchanger is lowered and the increase of the pressure in the refrigerant cycle can be suppressed. Furthermore, by driving both the compressor 8 and the cooling fan 2, the effect of suppressing the increase of the refrigerant pressure can be further promoted.

Still furthermore, when the controller 10 starts up at least one of the compressor 8 for the refrigerant cycle and the cooling fan 2 and also the air blowing fan for blowing air to the evaporator 5 is stopped, the refrigerant pressure at the low pressure side can be more rapidly reduced.

Furthermore, the compressor 8 for the refrigerant cycle is constructed by a displacement variable compressor, and the pressure reducing unit is started up while the controller 10 controls the capacity of the displacement variable compressor at the condition detection time. In this case, by controlling the start-up of the compressor, quick increase of the refrigerant pressure at the high-pressure side at the start-up time of the compressor can be suppressed.

Furthermore, by detecting that the refrigerant pressure in the refrigerant cycle 1 reaches a predetermined value, the control can be performed so as to be adaptable to quick variation when the condition detection is carried out.

Furthermore, when the refrigerant pressure at the discharge side of the compressor 8 is detected by the discharge pressure sensor 9, it is unnecessary to newly provide a condition detecting unit because an existing discharge pressure sensor equipped to the refrigerant cycle is also usable as the condition detecting means.

Second Embodiment

This embodiment is different from the first embodiment in that temperature data are used for the condition detection based on the condition detecting unit. In the supercritical refrigerant cycle, when refrigerant is sealed at some cycle sealing density, if the cycle average temperature at that time is increased, the sealed refrigerant falls into the supercritical state, and the pressure is determined by the temperature at that time. Therefore, according to this embodiment, the refrigerant detection is detected by detecting the refrigerant temperature.

Next, the second embodiment will be described with reference to FIGS. 8 to 17. The same constituent elements as the first embodiment are represented by the same reference numerals.

FIG. 8 is a diagram showing the construction of a refrigeration cycle device for a vehicle according to the second embodiment. As shown in FIG. 8, the refrigerant cycle 20 includes a compressor 8, a discharge temperature sensor 13 serving as an example of a temperature detecting unit and a first temperature detecting unit for detecting refrigerant temperature at the high pressure side, a gas cooler 3 corresponding to a high-pressure side heat exchanger, an expansion valve 4 serving as a pressure reducing unit, an evaporator 5 corresponding to a low-pressure side heat exchanger, a low-pressure side temperature sensor 13a for detecting the refrigerant temperature at the low pressure side of the refrigerant cycle, an accumulator 6 for separating the refrigerant into gas-phase refrigerant and liquid-phase refrigerant and feeding the gas-phase refrigerant to the suction portion of the compressor 8, and a relief device 7 disposed at the low pressure side corresponding to the suction portion side of the compressor 8, which are successively and annularly disposed through pipes. A cooling fan 2 is provided to the gas cooler 3 to be opposite with each other.

The operation of an ignition switch 11, the detection value of a discharge temperature sensor 13, the detection value of a post-evaporation temperature sensor 14, the detection value of a fin temperature sensor 15, the detection value of an air blow-out temperature sensor 16, the operation state of the compressor 8 and the operation state of the cooling fan 2 are input to a controller 17 (ECU) as a control unit for controlling the refrigerant cycle 20, and the operation of an air conditioner switch is also input.

The controller 17 has a timer 12, and it can count a time lapse or the like at the driving or stop time of each equipment constituting the refrigerant cycle 20. The controller 17 controls the compressor 8, the cooling fan 2, the expansion valve 4, etc. according to various kinds of input data and pre-set programs.

FIG. 9 is a diagram showing the construction of a vehicle refrigeration cycle device for judging the refrigerant pressure on the basis of various kinds of monitored temperature data achieved without directly detecting refrigerant temperature to control the refrigerant cycle. As shown in FIG. 9, the refrigerant cycle 30 is equipped with the compressor 8, the gas cooler 3 corresponding to a high-pressure side heat exchanger, the expansion valve 4 serving as a pressure reducing unit, the evaporator 5 corresponding to a low-pressure side heat exchanger, the accumulator 6 for separating the refrigerant into gas-phase refrigerant and liquid-phase refrigerant and feeding the gas-phase refrigerant to the suction port of the compressor 8, and the relief device 7 disposed at the low pressure side corresponding to the suction portion side of the compressor 8, which are successively and annularly connected to one another through pipes. The cooling fan 2 is provided to the gas cooler 3 to be opposite with each other.

The operation of the ignition switch 11, the detection value of a temperature sensor 18 in the engine compartment, the detection value of an outside air temperature sensor 19, the detection value of a solar radiation temperature sensor 21, the detection value of an passenger compartment temperature sensor 22, the operation state of the compressor 8 and the operation condition of the cooling fan 2 are input to a controller 23 (ECU) serving as a control unit for controlling the refrigerant cycle 30, and the operation of an air conditioner switch (not shown) is also input to the controller 23.

The controller 23 has a timer 12 and can count a time lapse at the driving or stop time of each equipment constituting the refrigerant cycle 30. The controller 23 controls the compressor 8, the cooling fan 2, etc. according to various kinds of input data and preset programs.

Next, FIG. 10 is a diagram showing the construction of a vehicle refrigeration cycle device for controlling a refrigerant cycle 40 on the basis of various kinds of monitored temperature data associated with the engine. As shown in FIG. 10, the refrigerant cycle 40 includes the compressor 8, the gas cooler 3 corresponding to a high-pressure side heat exchanger, the expansion valve 4 serving as a pressure reducing unit, the evaporator 5 corresponding to a low-pressure side heat exchanger, the accumulator 6 for separating the refrigerant into gas-phase refrigerant and liquid-phase refrigerant and feeding the gas-phase refrigerant to the suction portion of the compressor 8, and the relief device 7 disposed at the lower pressure side corresponding to the suction portion side of the compressor 8, which are successively and annularly connected to one another through pipes. The cooling fan 2 is provided to the gas cooler 3 to be opposite with each other.

The operation of the ignition switch (not shown), engine water temperature data, engine intake air temperature data, engine rotational number data, vehicle speed data, the operation state of the compressor 8 and the operation state of the cooling fan 2 are input to a controller 24 (ECU) serving as a control unit for controlling the refrigerant cycle 40, and the operation of the air conditioner switch (not shown) is also input to the controller 24.

Furthermore, the controller 24 has a timer 12 and can count a time lapse at the driving or stop time of the respective equipment constituting the refrigerant cycle 40. The controller 24 controls the compressor 8, the cooling fan 2, etc. according to various kinds of input data and preset programs.

Next, the operation of the vehicle refrigeration cycle device shown in FIGS. 8, 9 and 10 and the variation of the refrigerant pressure during the operation concerned will be described with reference to FIGS. 11 and 12. FIG. 11 is a time chart showing the relationship between the variation of the refrigerant temperature or each kind of monitored temperature and the variation of the refrigerant pressure in the vehicle refrigeration cycle devices shown in FIGS. 8, 9 and 10. FIG. 12 is a flowchart showing the control processing of controlling the compressor 8 on the basis of the various kinds of temperature data to reduce the refrigerant pressure in the vehicle refrigeration cycle devices shown in FIGS. 8, 9 and 10 (routine D).

As shown in FIG. 12, first, when the ignition (IG) switch is set to ON or the engine is driven (step S100), it is determined whether the compressor 8 is stopped or not (step Sill). When the compressor is driven, the refrigerant pressure in the refrigerant cycle 20, 30, 40 is stable, and some difference occurs between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side. Furthermore, it is estimated that the refrigerant temperature T detected by the discharge temperature sensor 13 and the various kinds of monitored temperature data are equal to fixed values (see FIG. 11). When it is determined in step S111 that the compressor 8 is not stopped, the determination of the step S111 is repeated again. Then, if it is determined that the compressor 8 is stopped, after a predetermined time t1′ described later elapses, the detection of the condition detecting unit is started, thereby carrying out the reset processing. At this time, the difference occurring between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side in the refrigerant cycle 1 is reduced with time lapse from the stop of the compressor 8, and both the refrigerant pressure values are finally equal to each other. Then, after a time further elapses, the refrigerant pressure thus equalized is increased by the effect from the outside air temperature and the effects of the heat radiation from the engine compartment and heat retention which are caused by the driving of the engine at the vehicle travel time or the like (see FIG. 11).

In the refrigerant cycle 20 shown in FIG. 8, it is determined whether the refrigerant temperature T based on the detection of the discharge temperature sensor 13 is equal to a predetermined value T1 or more (step S130 in FIG. 12). Likewise, when the high-pressure state of the refrigerant is determined on the basis of the detection values of the respective kinds of temperature sensors, it is determined whether the detection temperature data of the post-evaporation temperature sensor 14, the fin temperature sensor 15 and the blow-out temperature sensor 16 respectively are above predetermined values T2, T3, T10 respectively (step S130).

Furthermore, in the refrigerant cycle shown in FIG. 9, in order to determine the high pressure state of the refrigerant on the basis of the detection values of the various kinds of temperature sensors, it is likewise determined whether the respective detection temperature data of the temperature sensor 18 in the engine compartment, the outside air temperature sensor 19, the solar radiation temperature sensor 21 and the passenger compartment temperature sensor 22 are above predetermined values T4, T8, T9 or T7 (step S130).

In the refrigerant cycle 40 shown in FIG. 10, in order to determine the high pressure state of the refrigerant on the basis of the detection values of the various kinds of temperature sensors or various kinds of engine data, it is likewise determined whether the respective detection data of the engine water temperature data and the engine intake air temperature data are above a predetermined value T5 and above a predetermined value T6, or it is determined whether the respective detection data of the engine rotational number data and the vehicle speed data are above predetermined values (step S130).

When it is determined that each detection data as described above does not reach the corresponding predetermined value, the determination of the step S130 is repeated again. If it is determined that each detection data is above the corresponding predetermined value, the processing of starting up the compressor 8 is carried out (step S131). At this time, the refrigerant pressure in each refrigerant cycle is divided into the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side, and thus the difference in pressure occurs between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side again in connection with the start-up of the compressor (see FIG. 11).

Furthermore, after the compressor 8 is started up, the counting of the timer t2 is started by the timer 12 (step S132). In step S133, the counting of the timer t2 is continued until it reaches t2′ and if it is determined that the counting of the timer t2 reaches t2′, the compressor 8 during operation is stopped (step S134).

With respect to the refrigerant pressure in the refrigerant cycle in which a pressure difference occurs between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side, in connection with the stop of the compressor 8, the refrigerant pressure at the high pressure side is reduced while the refrigerant pressure at the low pressure side is increased, and thus the difference therebetween is reduced, so that both the refrigerant pressure values become equal to each other again and the refrigerant pressure as a whole is lower than the control set pressure. Thereafter, the processing goes to the linked processing indicated by the linking mark K and goes to the determination of step S155 of FIG. 16 and the determination of step S160 of FIG. 17 in the second embodiment, thereby going to the step of starting the detection of the condition detecting unit.

If the refrigerant pressure in the refrigerant cycle is kept to a value lower than the control set pressure, the damage of the equipment in the refrigerant cycle can be prevented. However, when the refrigerant pressure in the refrigerant cycle 1 is likely to fall into the condition that it exceeds the control set pressure because of the effects of the outside air temperature, the head radiation from the engine compartment, heat retention, etc. due to the driving of the engine at the vehicle travel time or the like again, the processing of the step S131 is executed again and the compressor 8 is started up in order to prevent the equipment in the refrigerant cycle 1 from being damaged.

In the above-described control processing flow of FIGS. 3, 5, 7 and 12, when the counting of the timer t2 reaches the predetermined time t2′, it is estimated that the refrigerant pressure is not high, and thus the compressor, etc. are stopped. In contrast, the control processing flow of stopping the compressor 8 or the like when the refrigerant detection pressure is reduced to a predetermined value or less or when each kind of detection temperature is reduced to a predetermined value or less will be described.

FIG. 13 is a flowchart showing the control processing of stopping the compressor 8 or the like on the basis of the refrigerant pressure detection value. The detection of the refrigerant pressure is carried out by using the detection value based on the low-pressure side sensor 9 a provided at the low pressure side, for example.

As shown in FIG. 13, first, in the case where the ignition (IG) switch is set to ON or the engine is driven (step S140), the condition detecting unit further detects the condition that the refrigerant pressure is likely to exceed the control set pressure, and thus the processing of starting up the compressor 8 or the cooling fan 2 by the pressure reducing unit (step S141) is carried out, in step S142 it is determined whether the refrigerant pressure P based on the detection of the low-pressure side pressure sensor 9 a serving as the pressure detecting unit is equal to a predetermined value P10 or less.

When the refrigerant pressure is determined as being not more than a predetermined value P10, the refrigerant pressure is regarded as not being high, and the processing of stopping the compressor 8 or cooling fan 2 during operation is carried out (step S143). Furthermore, if the refrigerant pressure is determined as being higher than the predetermined value P10, the refrigerant pressure is regarded as being in high state, and thus the determination of the step S142 is repeated again.

The subsequent processing jumps to the linking mark E in the control flowchart shown in FIGS. 3, 5, 7 and 12 to carry out the above-described routine A, B, C or D. In the routine A, B, C or D, as the detection of the condition for stopping the compressor 8 or the like, the steps S114 to S116, S118, S124 to S126 and S132 to S134 are replaced by S142 and S143.

FIG. 14 is a diagram showing the flow of the control processing when the compressor 8 or the like is stopped on the basis of each kind of temperature detection data. The detection of various kinds of temperature is carried out by using temperature detection data based on the low pressure side temperature sensor 13 a, the post-evaporation temperature sensor 14, the fin temperature sensor 15, the air blow-out temperature sensor 16, the engine compartment temperature sensor 18 and the passenger compartment temperature sensor 22, for example.

As shown in FIG. 14, first, when the ignition (IG) switch is set to ON or the engine is driven (step S140), the condition that the pressure is likely to exceed the control set pressure is detected by the condition detecting unit and thus the processing of starting up the compressor 8 or the cooling fan 2 is carried out (step S141), it is determined in step S144 whether each kind of temperature detection data is not more than a predetermined value TX. If it is determined that each kind of temperature detection data is not more than the predetermined value TX, the refrigerant pressure is regarded as not being high, and thus the processing of stopping the compressor 8 or the cooling fan 2 during operation is carried out (step S145).

If it is determined that the temperature detection data T is still higher than the predetermined value TX, the refrigerant pressure is regarded as being in high state, and thus the determination of step S142 is repeated again. With respect to the details of the temperature predetermined value TX for each detected temperature, the predetermined value of the refrigerant temperature is represented by TA, the predetermined value of the post-evaporation temperature is represented by TG, the predetermined value of the fin temperature is represented by TH, the predetermined value of the air blow-out temperature is represented by TI, the predetermined value of the engine compartment temperature is represented by TB and the predetermined value of the passenger compartment temperature (inside air temperature) is represented by TC.

The subsequent processing jumps to the processing indicated by a linking mark F in the control flowchart shown in FIGS. 3, 5, 7 and 12 to execute the above-described routine A, B, C or D. In the routine A, B, C or D, as the detection of the condition that the compressor 8 or the like is stopped, when the processing using each kind of temperature detection data described above is carried out, the processing of the steps S114 to S116, S118, S124 to S126 and S132 to S134 are replaced by the processing of steps S144 and S145.

Next, the processing (reset processing) when the detection of the condition detecting unit is started will be described with reference to FIGS. 15, 16 and 17. It is assumed that this processing is applicable to all the control flows of the first embodiment, this (second) embodiment and a third embodiment described later. FIG. 15 is a diagram showing the control flow showing the processing when the timing of starting the detection of the condition detecting unit is determined with time lapse. FIG. 16 is a diagram showing the control flow showing the processing when the timing of starting the detection of the condition detecting unit is determined on the basis of the detection value of the refrigerant pressure. FIG. 17 is a diagram showing the control flow showing the processing when the timing of starting the detection of the condition detecting unit is determined on the basis of each kind of temperature data.

FIG. 15 shows the processing of carrying out the reset processing on the basis of time lapse. First, the ignition (IG) switch is set to ON or the engine is driven (step S150), it is determined whether the compressor 8 or the cooling fan 2 is stopped or not (step S151).

In step S151, when it is determined that the compressor 8 or the cooling fan 2 is not stopped, the determination of step S151 is repeated again. However, if it is determined that the compressor 8 or the cooling fan 2 is stopped, the counting of the timer t1 is started by the timer 12 in step S152. The counting of the timer t1 is continued until the count of the timer t1 is equal to a predetermined value t1′ or more. When the count of the timer t1 is equal to the predetermined value t1′ or more (step S153), the condition detecting unit starts the detection (step S154).

This processing is continued until the count of the timer t1 by the timer 12 is equal to the predetermined value t1′ or more, whereby the execution of the processing of the condition detection is awaited until the refrigerant pressure in the refrigerant cycle is estimated to be under the condition that it is equalized in the refrigerant cycle after the compressor 8 or the cooling fan 2 is stopped, and the reset processing in the control flow is carried out. Then, when the reset processing is completed, the processing jumps to the above-described routine A, B, C, D, the following routine G, H, I or J, and each routine is executed.

FIG. 16 shows the processing flow of executing the reset processing by using a detection value of the refrigerant pressure. First, when the ignition (IG) switch is set to ON or the engine is driven (step S150), it is determined whether the compressor 8 or the cooling fan 2 is stopped or not (step S151).

If it is determined in step S151 that the compressor 8 or the cooling fan 2 is not stopped, the determination of the step S151 is repeated again. On the other hand, if it is determined that the compressor 8 or the cooling fan 2 is stopped, it is determined in step S155 whether the refrigerant pressure based on the detection of the discharge pressure sensor 9, etc. is equal to a predetermined value P3 or less. This corresponds to the detection of increase of the refrigerant pressure caused by the outside air temperature, the heat radiation from the engine compartment due to start-up of the engine during vehicle travel, heat retention, etc.

This processing is repeated until the refrigerant pressure P is equal to the predetermined value P3 or less. If the refrigerant pressure P is equal to the predetermined value P3 or less, the condition detecting unit starts the detection (step s156). This processing is continued until the refrigerant pressure P is equal to the predetermined value P3 or less, whereby after the compressor 8 or the cooling fan 2 is stopped, the execution of the processing of the condition detection is awaited until the refrigerant pressure in the refrigerant cycle is estimated to be under the condition that the refrigerant pressure is stable, and the reset in the control flow is carried out. When the reset processing is completed, the processing jumps to the above-described routine A, B, C, D, the following routine G, H, I or J, and the processing of each routine is executed.

FIG. 17 shows the processing of executing the reset processing by using the detection value of each kind of temperature data. First, when the ignition (IG) switch is set to ON or the engine is driven (step S150), it is determined whether the compressor 8 or the cooling fan 2 is stopped (step S151).

When it is determined in step S151 that the compressor 8 or the cooling fan 2 is not stopped, the determination of the step S151 is repeated again. On the other hand, if it is determined that the compressor 8 or the cooling fan 2 is stopped, it is determined in step S160 whether each kind of detected temperature data T is equal to a predetermined value TY or more.

This processing corresponds to the detection of increase of the refrigerant pressure caused by the outside air temperature, the heat radiation from the engine compartment due to driving of the engine at the vehicle travel time, heat retention, etc. The predetermined value TY is set to a predetermined value TD when the refrigerant temperature is detected by the low-pressure side temperature sensor 13a provided to the low pressure side of the refrigerant cycle, for example. When the refrigerant temperature is estimated and determined on the basis of the detected temperature of the post-evaporation temperature sensor 14, the fin temperature sensor 15 or the air blow-out temperature sensor 16, the respective predetermined values are set to TJ, TK, TL. Furthermore, when the refrigerant pressure state is determined by using the detection value of the engine compartment temperature sensor 18, the predetermined value is set to TE, and when the refrigerant pressure state is determined by using the detection value of the passenger compartment temperature sensor 22, the predetermined value is set to TF.

This processing is repeated until each kind of detected temperature data T is equal to a predetermined value TY or more, and if it is equal to the predetermined value TY or more, the condition detecting unit starts the detection (step S161). This processing is continued until each kind of detection temperature data T is equal to the predetermined value TY or more, whereby after the compressor 8 or the cooling fan 2 is stopped, the execution of the processing of the condition detection is awaited until the refrigerant pressure in the refrigerant cycle is estimated to be under the condition that it is equalized, and the reset in the control flow is carried out. When this reset processing is completed, the processing jumps to the above-described routine A, B, C, D, the following routine G, H, I or J, and each routine is executed.

As described above, in the vehicle refrigerant cycle of this embodiment, the condition detecting unit is constructed by the discharge temperature sensor 13 (first temperature detecting unit) for detecting that the refrigerant temperature in the refrigerant cycle 20, 30, 40 reaches the predetermined value. In the case of this construction, the refrigerant pressure in the refrigerant cycle can be surely determined by carrying out the condition detecting on the basis of the refrigerant temperature. Furthermore, it is unnecessary to newly provide a first temperature detecting unit by using the existing discharge temperature sensor provided to the refrigerant cycle as the first temperature detecting unit.

Furthermore, the vehicle refrigeration cycle device of this embodiment is equipped with the low-pressure side pressure sensor 9 a for detecting the condition that the refrigerant pressure is likely to exceed the control set pressure of the refrigerant cycle 20, 30, 40 when the engine of the vehicle is driven or the ignition switch of the vehicle is set to ON and also the compressor 8 for the refrigerant cycle is under the stop state. Furthermore, the controller 17, 23, 24 is provided for starting up at least one of the compressor 8 and the cooling fan 2 in order to reduce the refrigerant pressure at the low pressure side of the refrigerant cycle 20, 30, 40 at the condition detection time. Furthermore, the control set pressure is set in prospect of the increase of the pressure in the refrigerant cycle 20, 30, 40 after the ignition switch is set to OFF. According to this construction, the increase of the refrigerant pressure which is caused by the heat from the engine, etc. at the vehicle travel time can be suppressed, and the damage of the equipment constituting the refrigerant cycle 20, 30, 40 can be prevented before it happens.

Furthermore, when the control set pressure is set to be lower than the lowest withstanding set pressure of the refrigerant cycles 20, 30, 40, a refrigeration cycle device for a vehicle that can warrant the functions of the respective functional parts can be achieved.

Still furthermore, when the control set pressure is set to be lower than the set pressure of the relief device 7 for protecting the equipment constituting the refrigerant cycle 20, 30 40, the refrigerant cycle can be protected without making the relief function in the increase of the refrigerant pressure at high temperature.

Still furthermore, when the first temperature detecting unit is constructed by the post-evaporation temperature sensor 14, the fin temperature sensor 15 or the air blow-out temperature sensor 16, the high temperature state of the refrigerant temperature can be estimated by detecting each kind of temperature data, and thus the refrigerant pressure state in the refrigerant cycle can be determined.

Still furthermore, when the condition detecting unit is constructed by the second temperature detecting unit for detecting whether any one of the temperature in the engine compartment and the temperature in the passenger compartment reaches a predetermined value, the refrigerant pressure state in the refrigerant cycle can be determined by carrying out the condition detection on the basis of each kind of temperature data.

When the temperature in the passenger compartment is detected on the basis of any one of the passenger compartment temperature sensor 22 for directly detecting the passenger compartment temperature, the outside air temperature sensor 19 for indirectly detecting the passenger compartment temperature and the solar radiation temperature sensor 21, it is unnecessary to newly provide a detecting unit by using each existing kind of sensor as the detecting unit for the passenger compartment temperature.

Still furthermore, when the second temperature detecting unit is constructed so that it is determined on the basis of the detection value of any one of the water temperature of the engine and the intake-air temperature of the engine whether the temperature in the engine reaches a predetermined value, the temperature in the engine compartment is determined by actively using each normally detected existing engine data, whereby it is unnecessary to newly provide a temperature detecting unit.

Still furthermore, when the condition detecting unit is constructed by a stop time detecting unit 12 (timer) for detecting whether the stop time of the compressor 8 reaches a predetermined time, the condition detecting is carried out by counting the stop time of the compressor 8, whereby the existing timer function equipped to the compressor 8 can be also used as the condition detecting unit, and thus it is unnecessary to newly provide a condition detecting unit.

Still furthermore, after at least one of the compressor 8 and the cooling fan 2 is started up by the controller 17, 23, 24, the controller 17, 23, 24 stops at least one of the compressor 8 and the cooling fan 2 during operation when a predetermined time elapses. When this control is adopted, the existing timer function provided to the refrigeration cycle device can be also used as the stop condition detecting unit, and thus it is unnecessary to newly provide a stop condition detecting unit.

When the controller 17, 23, 24 determines that the refrigerant pressure in the refrigerant cycle 20, 30, 40 is equal to a predetermined value or less after at least one of the compressor 8 and the cooling fan 2 is started up by the controller at the condition detection time, at least one of the compressor 8 and the cooling fan 2 during operation is stopped. When this control is adopted, the refrigerant pressure is detected and used for the stop condition detection, whereby the control can be performed so as to be able to quickly follow the variation of the refrigerant pressure.

When at the condition detection time the controller 17, 23, 24 determines that the refrigerant temperature at the low pressure side in the refrigerant cycle 20, 30, 40 is equal to a predetermined value or less or determines that any one of the post-evaporation temperature, the fin temperature and the air blow-out temperature is equal to a predetermined value or less, at least one of the compressor 8 and the cooling fan 2 is started up by the controller 17, 23, 24, the controller 17, 23, 24 stops at least one of the compressor 8 and the cooling fan 2 during operation.

When this control is adopted, the stop condition detecting is carried out on the basis of the refrigerant temperature, the refrigerant pressure in the refrigerant cycle can be properly determined. Furthermore, when the stop condition detection is carried out on the basis of the post-evaporation temperature, the fin temperature or the air blow-out temperature, the refrigerant pressure can be estimated and determined by detecting the temperature level of the refrigerant of the evaporator.

Furthermore, when at the condition detection time the controller 17, 23, 24 determines that any one of the temperature in the engine compartment and the temperature in the passenger compartment is equal to a predetermined value or less after at least one of the compressor 8 and the cooling fan 2 is started up by the controller, the controller stops at least one of the compressor 8 and the cooling fan 2 during operation. When this control is adopted, the refrigerant pressure state in the refrigerant cycle can be determined by carrying out the stop condition detection by using each kind of temperature data.

When a predetermined time elapses after at least one of the compressor 8 and the cooling fan 2 is stopped, the condition detecting unit starts the detection. In this case, the existing timer function provided to the refrigerant cycle is also used to detect the reset processing timing, whereby it is unnecessary to newly provide a detecting unit.

Furthermore, when it is determined that the refrigerant pressure at the high pressure side in the refrigerant cycle 20, 30, 40 is equal to a predetermined value or less after at least one of the compressor 8 and the cooling fan 2 is stopped, the condition detecting unit starts the detection. In this case, the reset processing timing is detected by detecting the refrigerant pressure, whereby the reset processing can be carried out so as to be able to quickly follow the variation of the refrigerant pressure.

Furthermore, when it is determined that the refrigerant temperature at the low pressure side in the refrigerant cycle 20, 30, 40 reaches a predetermined value after at least one of the compressor 8 and the cooling fan 2 is stopped or it is determined that any one of the post-evaporation temperature, the fin temperature and the air blow-out temperature reaches a predetermined value, the condition detecting unit starts the detection. In this case, when the reset processing timing is detected on the basis of the refrigerant temperature, the refrigerant pressure in the refrigerant cycle can be properly determined and the reset processing can be performed. Furthermore, when the reset processing timing is detected on the basis of the post-evaporation temperature, the fin temperature or the air blow-out temperature, the refrigerant pressure can be estimated and determined by detecting the refrigerant temperature level of the evaporator.

Furthermore, after at least one of the compressor 8 and the cooling fan 2 is stopped, when it is determined that any one of the temperature in the engine compartment and the temperature in the passenger compartment reaches a predetermined value, the condition detecting unit starts the detection. In this case, the reset processing timing is detected by using each kind of temperature data, whereby the reset processing based on the estimation of the refrigerant pressure state in the refrigerant cycle can be carried out.

Third Embodiment

In the third embodiment, under the state that the ignition (IG) switch is set to OFF, the compressor or the cooling fan is started up at the condition detection time, and then the stop control is carried out as in the case of FIGS. 3, 5 and 12. The different point of the third embodiment from the first and second embodiments resides in that an electrically-driven compressor and an electrically-driven cooling fan is controlled in place of the compressor 8 and the cooling fan 2 to keep the refrigerant pressure proper. The third embodiment will be described hereunder with reference to FIGS. 18 to 21.

FIG. 18 is a control flowchart showing the processing of reducing the refrigerant pressure by controlling the electrically-driven compressor on the basis of the detection value of the refrigerant pressure when the ignition (IG) switch is set to OFF.

In this control flow shown in FIG. 18, first, when the ignition (IG) switch is set to OFF (step S170), it is determined whether the electrically-driven compressor is stopped (step S171). When the electrically-driven compressor is not stopped, with respect to the refrigerant pressure in the refrigerant cycle, a difference occurs between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side. If it is determined in step S171 that the electrically-driven compressor is not stopped, the determination of the step S171 is repeated again. However, if it is determined that the electrically-driven compressor is stopped, the reset processing described above is carried out, and the condition detecting unit starts the detection.

Then, it is determined in step S172 whether the refrigerant pressure P based on the detection of the discharge pressure sensor 9 is equal to a predetermined value P′ or more. When the electrically-driven compressor is stopped, the refrigerant pressure P is increased by the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention due to the driving of the engine at the vehicle travel time or the like, etc. When it is determined that this refrigerant pressure reaches the predetermined value P′, the processing of starting up the electrically-driven compressor is carried out (step S173).

Furthermore, when it is determined that the refrigerant pressure does not reach the predetermined value P′, the determination of the step S172 is repeated again. At this time, the refrigerant pressure in the refrigerant cycle is divided into the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side again and a pressure difference occurs therebetween. Furthermore, after the electrically-driven compressor is started up, the counting of the timer t2 is started by the timer 12 (step S174). In step S175, the counting is continued until the count of the timer t2 reaches t2′, and if it is determined that the count of the timer t2 reaches t2′, the electrically-driven compressor during operation is stopped (step S176).

In the refrigerant cycle in which a pressure difference occurs between the high pressure side and the low pressure side, the refrigerant pressure at the high pressure side is reduced and the refrigerant pressure at the low pressure side is increased by the stop of the electrically-driven compressor at step S176, so that the pressure difference therebetween is reduced. Therefore, Both the refrigerant pressure values at the high and low pressure sides are equalized to each other, and the whole refrigerant pressure is controlled to be lower than the control set pressure as a whole. Thereafter, the processing goes to the processing indicated by the linking mark K, and thus goes to the determination of step S155 of FIG. 16 and the determination of step S160 of FIG. 17 shown in the second embodiment, whereby the processing goes to the step of starting the detection of the condition detecting unit.

If the refrigerant pressure in the refrigerant cycle is kept to be lower than the control set pressure as described above, the equipment in the refrigerant cycle can be prevented from being damaged. However, in the case of the condition that the refrigerant pressure in the refrigerant cycle 1 is likely to exceed the control set pressure because of the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention, etc. which are caused due to the driving of the engine at the vehicle travel time or the like, the processing of the step S173 is executed again to prevent the damage of the equipment in the refrigerant cycle, thereby starting up the electrically-driven compressor.

Next, FIG. 19 is a control flowchart showing the processing of controlling the electrically-driven cooling fan on the basis of the detection value of the refrigerant pressure to reduce the refrigerant pressure when the ignition (IG) switch is set to OFF.

In this control flow shown in FIG. 19, first, when the ignition (IG) switch is set to OFF (step S170), it is determined whether the compressor is stopped (step S177). If the compressor is not stopped, with respect to the refrigerant pressure in the refrigerant cycle, a pressure difference occurs between the refrigerant pressure at the high pressure side and the refrigerant pressure at the low pressure side. If it is determined in step S177 that the compressor is not stopped, the determination of the step S177 is repeated again. However, if it is determined that the compressor is stopped, the above-described reset processing is executed, and the condition detecting unit starts the detection.

Then, it is determined in step S178 whether the refrigerant pressure P based on the detection of the discharge pressure sensor 9 is equal to a predetermined value P′ or more. When the compressor is stopped, the refrigerant pressure P is increased by the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention, etc. due to the driving of the engine at the vehicle travel time or the like, and if it is determined that this refrigerant pressure reaches the predetermined value P′, the processing of starting up the electrically-driven cooling fan is carried out (step S179).

If it is determined that the refrigerant pressure P does not reach the predetermined value P′, the determination of the step S178 is repeated again. At this time, the refrigerant pressure P in the refrigerant cycle is controlled to be lower than the predetermined value P′ because the refrigerant is cooled by the start-up of the electrically-driven cooling fan. Furthermore, after the electrically-driven cooling fan is started up, the counting of the timer t2 is started by the timer 12 (step S180). In step S181, the counting of the timer t2 is continued until the count of the timer t2 reaches t2′. If it is determined that the count of the timer t2 reaches t2′, the electrically-driven cooling fan during operation is stopped (step S182).

The refrigerant pressure in the refrigerant cycle which is reduced to be lower than the predetermined value P′ is gradually increased by the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention, etc. due to the driving of the engine at the vehicle travel time or the like. Thereafter, the processing goes to the processing indicated by the linking mark K, and thus goes to the determination of the step S155 of FIG. 16 and the determination of the step S160 of FIG. 17, whereby the processing goes to the step of starting the detection of the condition detecting unit.

If the refrigerant pressure in the refrigerant cycle is kept to be lower than the control set pressure as described above, the equipment in the refrigerant cycle can be prevented from being damaged. However, in the case of the condition that the refrigerant pressure in the refrigerant cycle is likely to exceed the control set pressure because of the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention, etc. which are caused due to the driving of the engine at the vehicle travel time or the like, the processing of the step S179 is executed again to prevent the damage of the equipment in the refrigerant cycle, thereby starting up the electrically-driven cooling fan.

Next, FIG. 20 is a control flowchart showing the processing of controlling the electrically-driven cooling fan based on each kind of temperature data T to reduce the refrigerant pressure when the ignition (IG) switch is set to OFF. In this control flow, first, when the ignition (IG) switch is set to OFF (step S170), it is determined whether the compressor is stopped (step S177). Furthermore, it is considered that the refrigerant temperature detected by the discharge temperature sensor 13 or the like and each kind of monitored temperature data are fixed values.

If it is determined in step S177 that the compressor is not stopped, the determination of the step S177 is repeated again. When the compressor is stopped, the refrigerant pressure is increased by the effect of the outside air temperature, the effect of the heat radiation from the engine compartment, the heat retention, etc. due to the driving of the engine at the vehicle travel time or the like.

When it is determined whether the compressor is stopped, in the refrigerant cycle 20 shown in FIG. 8, it is determined whether the refrigerant temperature T based on the detection of the discharge temperature sensor 13 is equal to a predetermined value T′ or more (step S183). Likewise, when the high-pressure state of the refrigerant is determined on the basis of the detection value of each kind of temperature sensor, it is determined whether each detection temperature data T of the post-evaporation temperature sensor 14, the fin temperature sensor 15 or the air blow-out temperature sensor 16 is not less than a predetermined value T2, T3 or T10 (step S183).

In the refrigerant cycle 30 shown in FIG. 9, likewise, in order to determine the high-pressure state of the refrigerant on the basis of the detection value of each kind of temperature sensor, it is determined whether the detected temperature data T of each of the engine compartment temperature sensor 18, the outside air temperature sensor 19, the solar radiation temperature sensor 21 and the passenger compartment temperature sensor 22 is not less than a predetermined value T4, T8, T9 or T7 (step S183).

Alternatively, in the refrigerant cycle 40 shown in FIG. 10, likewise, when the high-pressure state of the refrigerant is determined on the basis of the detection value of each kind of temperature sensor or each kind of engine data, it is determined whether the detection data (T) of each of the engine water temperature data and the engine intake air temperature data is not less than a predetermined value T5, T6, or whether the detection data of each of the engine rotational number data and the vehicle speed data is not less than a predetermined value (step S183).

If it is determined whether each detection data (T) as described above does not reach the predetermined value (T′), the determination of the step S183 is repeated. However, if each detection data (T) is equal to a predetermined value (T′) or more, the processing of starting up the electrically-driven cooling fan is carried out (step S184). At this time, the refrigerant pressure in each refrigerant cycle acts to reduce the electrically-driven cooling fan in connection with the start-up of the electrically-driven cooling fan.

Furthermore, after the electrically-driven cooling fan is started up, the counting of the timer t2 is started by the timer 12 (step S186). In step S186, the counting of the timer t2 is continued until the count of the timer t2 reaches t2′, and if it is determined that the count of the timer t2 reaches t2′, the refrigerant pressure is regarded as not being high, and thus the electrically-driven cooling fan during operation is stopped (step S187).

Thereafter, the processing goes to the processing indicated by the linking mark K and thus goes to the determination of the step S155 of FIG. 16 or the determination of the step S160 of FIG. 17 in the second embodiment, whereby the processing advances to the step of starting the detection of the condition detecting unit. Furthermore, the electrically-driven fan may be controlled to be continually driven when the refrigerant pressure is still higher than the control set pressure as a whole.

If the refrigerant pressure in the refrigerant cycle is kept to be lower than the control set pressure as described above, the equipment in the refrigerant cycle can be prevented from being damaged. However, in the case of the condition that the refrigerant pressure in the refrigerant cycle 1 is likely to exceed the control set pressure because of the effect of the outside air temperature, the effect of the heat radiation from,the engine compartment and the heat retention, etc. which are caused due to the driving of the engine at the vehicle travel time or the like, the processing of the step S185 is executed again to prevent the damage of the equipment in the refrigerant cycle, thereby starting up the electrically-driven cooling fan. The control flow shown in FIG. 20 represents the flow of controlling the electrically-driven cooling fan, however, the same effect can be achieved if it is replaced by the processing of controlling the electrically-driven compressor.

FIG. 21 is a control flowchart showing the processing of detecting the stop time of the compressor by the timer 12 when the ignition (IG) switch is set to OFF, regarding the refrigerant as being under a high pressure state when the detection time is equal to a predetermined time or more, and controlling the electrically-driven cooling fan to reduce the refrigerant pressure.

In this control flow, first, when the ignition (IG) switch is set to OFF (step S170), it is determined whether the compressor is stopped or not (step S177). If it is determined in step S177 that the compressor is not stopped, the counting of the timer t1 is started by the timer 12 to detect the stop time of the compressor in step S190.

The counting is continued until the count of the timer t1 is equal to t1′ or more (step S191), and if it is determined that the count of the timer t1 is equal to t1′ or more, the refrigerant pressure is in the high pressure state, and thus the electrically-driven cooling fan is started up (step S192). At this time, the refrigerant pressure in the refrigerant cycle is controlled to be lower than the control set pressure because the refrigerant is cooled by starting up the electrically-driven cooling fan, for example.

Furthermore, after the electrically-driven cooling fan is started up, the counting of the timer t2 is started by the timer 12 (step S193). In step S194, the counting of the timer t2 is continued until it reaches t2′, and if it is determined that the count of the timer t2 reaches t2′, the electrically-driven cooling fan during operation is stopped (step S195).

When the refrigerant pressure in the refrigerant cycle is lower than the control set pressure, the refrigerant pressure is gradually increased by the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention due to the driving of the engine at the vehicle travel time or the like, etc. because of the stop of the engine. Thereafter, the processing goes to the processing indicated by the linking mark K, and thus goes to the determination of the step S155 of FIG. 16 or the determination of the step S160 of FIG. 17 in the second embodiment, whereby the processing advances to the step of starting the detection of the condition detecting unit.

If the refrigerant pressure in the refrigerant cycle is kept to a value lower than the control set pressure as described above, the equipment in the refrigerant cycle can be prevented from being damaged. However, in the case of the condition that the refrigerant pressure in the refrigerant cycle is likely to exceed the control set pressure because of the effect of the outside air temperature, the effect of the heat radiation from the engine compartment and the heat retention, etc. which are caused due to the driving of the engine at the vehicle travel time or the like, the processing of the step S192 is executed again to prevent the damage of the equipment in the refrigerant cycle, thereby starting up the electrically-driven cooling fan. The control flow shown in FIG. 21 represents the flow of controlling the electrically-driven cooling fan, however, the same effect can be achieved if it is replaced by the processing of controlling the electrically-driven compressor.

With respect to the start-up of the electrically-driven compressor and the electrically-driven cooling fan, they are started up when the residual amount of the battery voltage is equal to a predetermined voltage or more. The driving of the electrically-driven compressor and the electrically-driven cooling fan may be controlled while feeding back the refrigerant pressure state in the refrigerant cycle by monitoring the various kinds of temperature data of the discharge pressure sensor 9, the discharge temperature sensor 13, etc.

Furthermore, the time t1′ from the stop of the compressor to the start-up of the compressor may be controlled to be varied in accordance with the outside air temperature. For example, when the outside air temperature is not less than 30° C., t1′ is set to 5 minutes, and when the outside air temperature is less than 30° C., the compressor is not started up.

As described above, the vehicle refrigeration cycle device according to this embodiment is equipped with: the condition detecting unit for detecting the condition that the refrigerant pressure is likely to exceed the control set pressure of the refrigerant cycle when the ignition switch for the vehicle is under OFF state; and the pressure reducing unit for reducing the refrigerant pressure at the low pressure side when the condition is detected. The pressure reducing unit starts up at least one of the electrically-driven compressor and the electrically-driven cooling fan by the control unit when the condition is detected.

According to this construction, under the state that the ignition switch is set to OFF, the start-up is carried out by using power even after the ignition switch is set to OFF, and thus this construction is adaptable to the increase of the refrigerant pressure. Furthermore, the refrigerant pressure at the start-up time can be set to be near to the control set pressure, and thus the loss of the driving force can be reduced.

Furthermore, the condition detecting unit is constructed by the discharge pressure sensor 9 for detecting whether the refrigerant pressure in the refrigerant cycle reaches a predetermined value. In the case of this construction, the refrigerant pressure is detected and used for the condition detection, whereby the control can be performed while quickly following the variation of the refrigerant pressure.

Furthermore, the condition detecting unit is constructed by the discharge temperature sensor 13 as the temperature detecting unit for detecting whether the refrigerant temperature in the refrigerant cycle reaches a predetermined value. In the case of this construction, the refrigerant pressure in the supercritical refrigerant cycle can be surely determined by carrying out the condition detection on the basis of the refrigerant temperature.

Furthermore, the condition detecting unit is constructed by the engine compartment temperature sensor 18 or the passenger compartment temperature sensor 22 as the second temperature detecting unit for detecting whether any one of the temperature in the engine compartment and the temperature in the passenger compartment reaches the predetermined value. In the case of this construction, the refrigerant pressure state in the supercritical refrigerant cycle can be determined by carrying out the condition detection with the various kinds of temperature data.

Still furthermore, the condition detecting unit is constructed by the timer 12 for detecting whether the stop time of the compressor 8 in the refrigerant cycle reaches a predetermined time. In the case of this construction, the condition detecting is carried out by counting the stop time of the compressor, whereby the existing timer function provided to the compressor can be also used as the condition detecting unit, and thus it is unnecessary to newly provide a condition detecting unit.

Other Embodiments

The present invention is not limited to the above-described embodiments, and various kinds of modifications may be made as follows without departing from the subject matter of the present invention.

For example, the refrigeration cycle devices of the above-described embodiments may be constructed by a refrigerant cycle having an internal heat exchanger. The internal heat exchanger is a heat exchanger for heat-exchanging refrigerant flowing between a heat exchanger in the passenger compartment and a heat exchanger out of the vehicle with refrigerant flowing out from the accumulator and sucked into the compressor.

The refrigeration cycle devices of the above-described embodiments may be constructed by an ejector cycle using an ejector. The ejector includes a nozzle portion for converting the pressure energy of flow-in refrigerant to the speed energy of the refrigerant so that the refrigerant is reduced in pressure and expanded, a mixing portion for mixing the high-speed refrigerant stream ejected from the nozzle portion with gas-phase refrigerant which is evaporated in the evaporator by the high-speed refrigerant stream ejected from the nozzle portion while sucking the gas-phase refrigerant, and a diffuser portion for converting the speed energy to the pressure energy while mixing the refrigerant ejected from the nozzle with the refrigerant sucked from the evaporator, thereby increasing the refrigerant pressure.

Furthermore, in all the above-described embodiments, the control set pressure may be set in prospect of the increase of the pressure in the refrigerant cycle 1 after the ignition switch is set to OFF. Furthermore, the control set pressure may be set in prospect of the pressure increase in the refrigerant cycle 1 caused by the residual heat of the engine after the ignition switch is set to OFF.

This is because the exhaust heat of the engine after the ignition switch is set to OFF stays the engine compartment, and thus the ambient temperature of the refrigerant cycle is increased, so that the inner pressure of the refrigerant cycle is increased. In other words, the control set pressure may be set in prospect to the amount corresponding to the increase of the temperature, that is, the pressure increase of the inner pressure of the refrigerant cycle.

The control set pressure is varied in accordance with the outside environment, for example, the outside air temperature, the earth's heat, the solar radiation temperature, the engine layout, the engine displacement or the layout of the air condition cycle because it is affected by the temperature in the engine compartment. For example, the control set pressure is different between the case where the outside air temperature is equal to 35° C. and the case where the outside air temperature is equal to 45° C. because the increasing degree of the refrigerant pressure is different between both the cases.

The control set pressure may be determined after the pressure increase corresponding to the environment varying every vehicle as described above is grasped or a situation which seems to be worst is assumed, in other words, the maximum pressure increase is grasped. For example, when the outside air temperature is equal to 35° C., the control set pressure is set to 10 MPa, and the when the outside air temperature is equal to 45° C., the control set pressure is set to 9 MPa.

Furthermore, with respect to the vehicle refrigeration cycle devices of all the embodiments, the inner pressure condition of the refrigerant cycle that the refrigerant pressure is likely to exceed the control set pressure of the refrigerant cycle is detected by the condition detecting unit, the compressor and/or the cooling fan is started up by the controller, and when the compressor and/or the cooling fan is afterwards stopped, neither lapse of a predetermined time nor restriction of the refrigerant pressure is required. Therefore, the detection of the condition detecting unit may be started again on the basis of the stop of the compressor or the cooling fan.

Still furthermore, the condition detecting unit of each of all the embodiments may be constructed so as to detect the condition that the refrigerant pressure is likely to exceed the control set pressure of the refrigerant cycle 1 under the state that the engine of the vehicle is not driven or the ignition switch of the vehicle is set to OFF. In this case, the condition detecting unit is adaptable to the increase of the refrigerant pressure without using the engine by using electric power, for example, a battery or the like.

Still furthermore, in the third embodiment, the inner pressure condition of the refrigerant cycle that the refrigerant pressure is likely to exceed the control set pressure during the operation of the engine may be executed under the state that the ignition switch of the vehicle is set to ON, and further when this condition is detected, that is, during the operation of the engine, the electrically-driven compressor or the electrically-driven cooling fan may be started up to reduce the pressure. In this case, the consumption of the battery voltage can be prevented.

Still furthermore, the electrically-driven compressor and the electrically-driven cooling fan of the third embodiment have the same action and effect as the first and second embodiments by applying to the compressor 8 and the cooling fan 2 of the first and second embodiments.

In the above-described embodiments, the vehicle refrigeration cycle device uses the refrigerant containing carbon dioxide as a main component. However, other refrigerant generally used for a refrigerant cycle can be used. For example, other refrigerant used in a super-critical state can be used as refrigerant.

While the invention has been described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the preferred embodiments and constructions. The invention is intended to cover various modification and equivalent arrangements. In addition, while the various elements of the preferred embodiments are shown in various combinations and configurations, which are preferred, other combinations and configuration, including more, less or only a single element, are also within the spirit and scope of the invention. 

1. A refrigeration cycle device for a vehicle, comprising: a refrigerant cycle through which refrigerant circulates; a condition detecting unit for detecting a condition that an inner pressure of the refrigerant cycle exceeds a control set pressure; and a pressure reducing means for reducing a pressure of the refrigerant at a low pressure side of the refrigerant cycle when the condition is detected.
 2. The refrigeration cycle device according to claim 1, wherein the control set pressure is set lower than a set value that is set for a lowest withstanding pressure in the refrigerant cycle.
 3. The refrigeration cycle device according to claim 1, wherein: the refrigerant cycle includes a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle; and the control set pressure is set to be lower than the set pressure of the relief device.
 4. The refrigeration cycle device according to claim 3, wherein the control set pressure is set to be lower than the set pressure of the relief device for protecting the equipment at the low pressure side of the refrigerant cycle by 0.5 MPa or more.
 5. The refrigeration cycle device according to claim 1, wherein the control set pressure is set in a range between 7 MPa and 12 MPa.
 6. The refrigeration cycle device according to claim 1, wherein the control set pressure is set in prospect of an increase of the pressure in the refrigerant cycle.
 7. The refrigeration cycle device according to claim 6, wherein the control set pressure is set in prospect of an increase of the pressure in the refrigerant cycle due to residual heat of an engine of the vehicle after an ignition switch of the vehicle is set to OFF.
 8. The refrigeration cycle device according to claim 6, wherein: the refrigerant cycle includes a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle; and the control set pressure is set to be lower than the set pressure of the relief device by 1.0 MPa or more.
 9. The refrigeration cycle device according to claim 1, wherein the refrigerant cycle includes a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, and a cooling fan for blowing air to the gas cooler, the device further comprising a control unit which controls operation of the refrigerant cycle, wherein the pressure reducing means starts up at least one of the cooling fan and the compressor by the control unit when the condition detecting unit detects the condition, and reduces the refrigerant pressure at the low pressure side in the refrigerant cycle.
 10. The refrigeration cycle device according to claim 1, wherein the refrigerant cycle includes a displacement variable compressor for compressing refrigerant in the refrigerant cycle, the device further comprising a control unit which controls operation of the refrigerant cycle, wherein the pressure reducing means starts up the displacement variable compressor while a discharge capacity of the displacement variable compressor is controlled by the control unit when the condition detecting unit detects the condition.
 11. The refrigeration cycle device according to claim 1, wherein the refrigerant cycle includes a compressor for compressing refrigerant, the compressor being driven by using an engine of the vehicle as a driving source, the device further comprising a control unit which controls operation of the refrigerant cycle, wherein the pressure reducing means starts up the compressor by the control unit to reduce the refrigerant pressure at the low pressure side when the condition detecting unit detects the condition.
 12. The refrigeration cycle device according to claim 11, wherein the condition detecting unit detects the condition while an engine of the vehicle is operated under a state where an ignition switch of the vehicle is set to ON.
 13. The refrigeration cycle device according to claim 9, wherein the compressor is constructed with an electrical compressor driven electrically.
 14. The refrigerant cycle according to claim 13, wherein the condition detecting unit detects the condition under a state where an ignition switch of the vehicle is set to OFF.
 15. The refrigeration cycle device according to claim 1, wherein the refrigerant cycle includes a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, an evaporator for evaporating refrigerant after being decompressed, a first fan for blowing air to the gas cooler, and a second fan for blowing air to the evaporator, the device further comprising a control unit which controls operation of the refrigerant cycle, wherein when the condition detecting unit detects the condition, at least one of the first fan and the compressor is driven and the second fan is stopped by the control unit.
 16. The refrigeration cycle device according to claim 1, wherein the condition detecting unit includes a pressure detecting unit for detecting whether the refrigerant pressure in the refrigerant cycle reaches a predetermined value.
 17. The refrigeration cycle device according to claim 16, wherein the pressure detecting unit includes a discharge pressure sensor for detecting the refrigerant pressure at a discharge side of a compressor in the refrigerant cycle.
 18. The refrigeration cycle device according to claim 1, wherein the condition detecting unit includes a first temperature detecting unit for detecting whether a refrigerant temperature in the refrigerant cycle reaches a predetermined value.
 19. The refrigeration cycle device according to claim 18, wherein the first temperature detecting unit includes a discharge temperature sensor for detecting a refrigerant temperature at a discharge side of a compressor of the refrigerant cycle.
 20. The refrigeration cycle device according to claim 18, wherein the first temperature detecting unit includes at least one of a post-evaporation temperature sensor for detecting a temperature of air passed through an evaporator of the refrigerant cycle, a fin temperature sensor for detecting a temperature of a fin of the evaporator, and an air blow-out temperature sensor for detecting a temperature of air to be blown into a passenger compartment of the vehicle.
 21. The refrigeration cycle device according to claim 1, wherein the condition detecting unit includes a second temperature detecting unit for detecting whether any one of a temperature in an engine compartment of the vehicle and a temperature in a passenger compartment of the vehicle reaches a predetermined value.
 22. The refrigeration cycle device according to claim 21, wherein the second temperature detecting unit determines the temperature of the passenger compartment based on at least one of detection values of an inside air temperature sensor for directly detecting the temperature of air in the passenger compartment, an outside air temperature sensor for indirectly detecting the temperature in the passenger compartment, and a solar radiation temperature sensor for detecting a solar radiation amount entering into the passenger compartment.
 23. The refrigeration cycle device according to claim 21, wherein the second temperature detecting unit determines on the basis of the detection value of any one of an engine water temperature and an engine intake air temperature whether the temperature in the engine compartment reaches the predetermined value.
 24. The refrigeration cycle device according to claim 1, wherein the condition detecting unit includes a stop time detecting unit for detecting whether a stop time of a compressor of the refrigerant cycle reaches a predetermined time.
 25. The refrigeration cycle device according to claim 1, further comprising a control unit for controlling operation of the refrigerant cycle, wherein the control unit starts up at least one of a cooling fan for blowing air to a gas cooler, and a compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when a predetermined time elapses.
 26. The refrigeration cycle device according to claim 1, further comprising a control unit for controlling operation of the refrigerant cycle, wherein the control unit starts up at least one of a cooling fan for blowing air to a gas cooler and a compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that a refrigerant pressure in the refrigerant cycle is equal to a predetermined value or less.
 27. The refrigeration cycle device according to claim 1, further comprising a control unit for controlling operation of the refrigerant cycle, wherein the control unit starts up at least one of a cooling fan for blowing air to a gas cooler and a compressor of the refrigerant cycle when the condition detecting unit detects the condition, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that the refrigerant temperature in the refrigerant cycle is equal to a predetermined value or less, or any one of a post-evaporation temperature, a fin temperature and an air blow-out temperature is equal to a predetermined value or less.
 28. The refrigeration cycle device according to claim 1, further comprising a control unit for controlling operation of the refrigerant cycle, wherein the control unit starts up at least one of a cooling fan for blowing air to a gas cooler and a compressor of the refrigerant cycle when the condition is detected, and then the control unit stops at least one of the compressor and the cooling fan during operation when the control unit determines that a temperature in an engine compartment of the vehicle or a temperature in a passenger compartment of the vehicle is equal to a predetermined value or less.
 29. The refrigeration cycle device according to claim 25, wherein when a predetermined time elapses after at least one of the compressor of the refrigerant cycle and the cooling fan is stopped, the condition detecting unit starts the detection.
 30. The refrigeration cycle device according to claim 25, wherein when control unit determines the refrigerant pressure in the refrigerant cycle is equal to a predetermined value or less after at least one of the compressor and the cooing fan is stopped, the condition detecting unit starts the detection.
 31. The vehicle refrigeration cycle device according to claim 25, wherein, when the control unit determines that any one of the refrigerant temperature in the refrigerant cycle reaches a predetermined value or a post-evaporation temperature, a fin temperature and an air blow-out temperature reaches a predetermined value after at least one of the compressor and the cooling fan is stopped, the condition detecting unit starts the detection.
 32. The refrigeration cycle device according to claim 25, wherein, when the control unit determines that a temperature in an engine compartment of the vehicle or a temperature in a passenger compartment of the vehicle is equal to a predetermined value or less after at least one of the compressor and the cooling fan is stopped, the condition detecting unit starts the detection.
 33. The refrigeration cycle device according to claim 1, wherein the refrigerant cycle uses refrigerant containing carbon dioxide as a main component
 34. The refrigeration cycle device according to claim 26, wherein when a predetermined time elapses after at least one of the compressor of the refrigerant cycle and the cooling fan is stopped, the condition detecting unit starts the detection.
 35. The refrigeration cycle device according to claim 27, wherein when a predetermined time elapses after at least one of the compressor of the refrigerant cycle and the cooling fan is stopped, the condition detecting unit starts the detection.
 36. The refrigeration cycle device according to claim 28, wherein when a predetermined time elapses after at least one of the compressor of the refrigerant cycle and the cooling fan is stopped, the condition detecting unit starts the detection. 